The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Amal, Carburation => Topic started by: Billybream on 08.01. 2019 07:28
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It me again investigating possible replacement for Mk1 930 Concentric, started last year but decided to overhaul my original carb, results were still not acceptable trying to overcome body distortion and slide wear so now back on the hunt.
Was leaning towards Mikuni but then discovered PWK and liked it's features and the JRC version.
Just think they are all over priced and was keen to try and get a cheaper option or source and by chance find SRM offer PWK30 for £50.00 complete with mounting flange on Ebay.
Will I be brave enough to try, the story continues.
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I bought one from SRM at £56 inc of postage for my A65, there is same carb from another ebayer at £16 i took a chance and bought 2 at 16 for other A65.
Before everybody starts shouting i know the jetting might be different and the jets are hard to get etc
watch this space...
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G'day Billy/Harvey.
I have two on my Cafe (twin carb head). The std jetting may be OK for a single carb application but trying to tune two is a nightmare. I had to change everything about 1 million times. I ended up trying 3 slides, 3 pilots, 5 needles and a few mains in all combinations. Kehin jets/parts fit straight in but are expensive, slides are 60 quid each.
Cheers
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G'day Billy/Harvey.
I have two on my Cafe (twin carb head). The std jetting may be OK for a single carb application but trying to tune two is a nightmare. I had to change everything about 1 million times. I ended up trying 3 slides, 3 pilots, 5 needles and a few mains in all combinations. Kehin jets/parts fit straight in but are expensive, slides are 60 quid each.
Cheers
I think you know what my next question is!
Only if you really want to, could you give me an idea what way you went with jetting.
Pretty please *smile*
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G'day HM
I ended up not too far from the std jetting. Slow jet #40 instead of the #38, air screw 2,1/4 turns out, 3.5 slide, JJH needle with clip in middle, 135 main jet. Std float height is 19mm but on an alloy head with the downdraft angle it will flood (same as a concentric) so set at 21mm. Fine tuning the needle is a nightmare as there is about 30 to choose from to cover 3 throttle positions.
One thing I really like is the internal "jet block" is removable so those tiny (10-15 thou) orifices can be cleaned properly.
Lots of info out there re tuning.
Cheers
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Thanks for that muskrat, I will have a go and see how I get on. I think they will have left China now so another couple of weeks till delivery.
Cheers
Derek
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Just received JRC (PWK) carb from SRM, pleased so far with quality but will be a month before I get around to fitting it. Need to strip it down and check what jets are fitted and source inline fuel filter. Paid £50.00 plus carriage so a good bit cheaper than equivalent Amal.
Appreciate might need alternative jets but they seem readily available and good bit of advice regarding tuning now available. Bought some Gorilla glue to affix flange to carb. Fuel inlet is 8mm so will need to adapt from 1/4" supply from tank.
SRM do not offer any application details or advice as they do with Mikuni, but for cost saving worth a try.
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G'day Billy.
When I bought mine from JRC the flange was attached with glue and a grub screw. It was very tight to remove as I use spigot to rubber to manifold.
Cheers
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I know Bill well at JRC who commissioned the PWKs and supplies them to dealers, including I suppose to SRM.
I Would caution people from assuming the cheap ones on ebay are the same carb. I have been meaning to order one off ebay and compare side by side, So I cant comment, However what I CAN tell you is the ones JRC supplies (And I am still a dealer for them) need no fiddling rejetting or other issues. They DO include a jet up and down from ones fitted, but you simply spec what the application is and it comes all dialed in.
I have sold a lot of these and no issues or significant problems. Every one has been fit and forget. Nor,,, have we had any problems fitting a pair and tuning them. (Bonnies and A65 BSA twins) The ONLY issue you WILL find is on a Norton with twin carbs (Generally I prefer a single carb on Norton twins). The adjusters are one sided so for a norton they supply an extended screw with flats and a small flat wrench to fit in between to fine tune. But Triumphs and BSA no issues.
Unlike a Mikuni VM carb which IS actually a Amal design sold under license to Mikuni, Some people complain about the looks of the flat slide JRC/PKW carbs as they dont look english. Fair enough,, but they DO work, and work very well.
The whole purpose of them was to offer a simple carb with minimal tuning needs and fiddly adjustments like a Amal concentric but without the massive quality problems of the stock Amals. The JRC/PKW delivers very nicely in that regard at a attractive price.
You might find the following useful: https://jrcengineering.com/technical-support/jrc-pwk-carb-instructions/
also
https://jrcengineering.com/wp-content/uploads/2017/09/JRC-PWK-CARB-TUNING.pdf
If you have specific issues, let me know as I speak to Bill and his team frequently, But be advised they do not deal direct with the public. Dealer only. That said, they are one of the nicest people I know in the Brit Bike industry and proud to know them.
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hi sluggo
the carbs do seem impressive and as a fan of mikuni carbs i am sure they are a stage better. but the main drawback for me is the sizing. i use a 28mm concentric on my plunger a10 and the recommended 30mm would mean opening up the inlet port? why no 28mm option?
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G'day Sluggo.
It's been quite a while since I bought my two. May have been Lowbrow who I got them off. I didn't get any extra main jets. I need the extended pilot screw to get to the right carb. It's a pain having to loosen the carb and turn it 45 degrees to get to it. I may be the only one to have twin carbs on an A10. I'll also have to get the cable choke and either run it through a splitter (like my throttle) or have two levers.
Tuning wise I have straight through exhaust with reverse cones, no filters, 357 cam and 10.5:1 comp so the std jetting didn't work. There are so many needles to play with it can get very confusing.
In saying all that I am still very happy with them.
A friend is using the OKO ones on his CB450 and is happy also.
Cheers
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The carb supplied by SRM does not state JRC anywhere, on the carb body its stamped PWK and the packaging box PWK30J. It came with seperate metal mounting flange, with 2 × grub screw fixing and no spare jets, but during communication SRM did say the carb was supplied by JRC.
So far I,m pleased with the appearance, finish and quality, as for function that's still to try.
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Fitted the SRM supplied PWK (JRC) 30mm carb today, changed the main and pilot jets, made up new fuel lines and installed inline filter, filled with fuel and pulled up the enricher and first kick she fired up, adjusted idle speed and was ticking over well. Discovered leak from serviceable filter, so switched her off.
Well impressed so far with this carb, just had to shorten mounting stud on L H and existing throttle cable fitted great. The supplied alloy mounting flange was gorrila glued to the carb and secured with grub screws supplied and had to source flange O Ring.
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Im glad it worked out (So far) I have been off line a bit, and just returned from our vacation home, However, in a twist of Irony right before we left, had a old shop customer out for a ride stop by, He said he was riding and decided to see if I was still at the same place.
The Mrs was upset figuring we would never leave the driveway on time, But it all worked out. Mark discussed the JRC/PWKs we fitted to his 68 Bonnie many years ago. Still working great and he is very pleased with them
(Duals) I still have his old Amals on the shelf and reminded him we should get together soon and Ill check over the carbs and see if they need adjustment, and return his old carbs to him.
The old original Amals had body distortion and warping. Slides kept sticking. I took an exhaust pipe expander and gentily tweaked the bores and then honed them with a cyl. boring tool. I expect they will warp again in use, But they are now functional albeit a bit sloppy with the slides. The idea is if he ever wishes to sell the bike he does have the original parts to include, But he stated he has no intention of going back to the Amals while in his ownership.
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As to missing bits (O ring) I cant comment on why the dealer failed to include that, They ship from JRC with a flange O ring.When replacing O rings always use a Nitrile or fuel compatible Oring. I cant say always, but I never liked the original slide springs. Way too soft and I like a firm response with the throttle. Based on my feedback as well as many other dealers and users, there is 2 slide springs usually supplied. The original soft spring and the firmer revised springs.
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As to choke cables, I never fitted or used them with the JRC/PWKs as the levers suffice, and cables become another issue on their own. (Anyone familiar with modern cable offerings understands this). However last year I have a friend with a collection of bikes and he got his dream bike.. (I told him he was better off with a BSA Goldstar, but some people, sigh...........) Anyrate, He had been after a Vincent for many years and bought a Rapide with a side car.
The Vincent issue with him is a long story in itself and not germaine.. However the Concentrics fitted were knackered badly, along with some other questionable maint by the DPO. I ordered him the JRC/PWK carbs and he wanted the cables for the chokes. We got them and a splitter and I also supplied a handle bar choke lever. The plan was to photograph it and document the install. (And alienate most of the Vinnie community) But to date it remains incomplete due to other time constraints and other issues. I do expect by summer it will be completed and the other repairs as well.
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One note on design,installs & sizing. It depends on the application. Since these carbs are often fitted to a wide variety of machines,,
(I have a Kawasaki KZ750B, which is a 750cc vertical twin and similar to a unit BSA/Triumph but it was fitted with CV carbs and problematic so fitting these JRC/PWKs to it as well)
But there is such a wide variety of mounts and designs. Some unit models used a phenolic insulating block which is quite thick. Hence long studs. Many concentrics use a thicker O ring and a odd setup of washers, cupped rubber bits and locking nut to secure the carbs. Many mouth breathing-knuckle dragging owners over tighten these and fail to understand you are only tightening to seal the Oring, NOT mash it down so tight it squeezes out the poor suffering O rings. This accelerates as well the warpage problems many Amals are prone too. But often, studs might be too long, or, if you need a heat and vibration insulator and wish to use a spacer/insulator, the studs may be of insufficient length.
So,, some fettling required..!! *smiley4*
As to the flange and spigots, The original bodies as supplied are spigot design. Because most applications are flange mount, JRC manufactured suitable flanges. Originally they were assured that a epoxy resin with the close machined fit would be indestructible and last forever, However early versions experienced failures, so I believe they changed Epoxys, and now fit a grub screw to help secure them. When I ordered the carbs for Jeff and the Vinnie, Because of the manifolds previously on the bike, I wanted to mount them racer style without flanges and requested them without flanges.**
Jeff Changed his mind and while the bike had some really questionable manifolds fitted (2 piece with lots of RTV ) He elected to order new manifolds from some supplier in the Vincent community, so we are back to flange mount again.
** Racer style. If you look at period race bikes and even some of todays classic racers, You will not see many Amals being raced with the exception of some of the Mk11s which is similar to the Mikuni VM style (Again, both the Mikuni VM and the Mk11 are Amal design). But you will see often times is tuned length intakes for the application. These are usually spigot mounts. Some run a alloy tube, some run flex pipe.
I have some Triumph race bikes and some of these were modded many years back with a variety of intakes and using the tuned length intakes. (Funny story here**)
I cant speak for everyone, But what we often sourced was from workplaces, I have used Commercial Sandblast hose, Naval and Maritime fuel and fluid hose, And food grade industrial hose that is chem resistant. So, in a pinch at the time, I couldnt find a good source for Jeffs project so I went to an industrial supplier and bought a radiator hose for a Caterpillar Diesel engine. Very attractive black thick wall material and chem resistant. Also some heavy duty stainless clamps, not cheesy hose clamps like you see on some cars, but really nice clamps with bolts for tightening. Since no longer needed, I will repurpose it for a cafe racer build but cost a small fortune.
**So funny story, *smile* I often would grill old guys who raced, And there was a local named George who was somewhat famous in local racing series, Sonny Burres, Glen Adams and several other nationally known racers rode for George. Most of these guys went to great lengths to throw off their competitors as well as closely guard their secrets. George fed me many absurd bits of misinformation over the years as a matter of habit, but eventually stopped telling me tall tales and gave me the facts (Which was appreciated).
So, they often fitted crazy or mismatched parts their race bikes knowing full well that other racers would copy it and detune or slow them down. At times they went to great lengths to do so with hidden modifications to make these work. One of which, Sonny went out and qualified with a Triumph with absurdly long tuned intakes using the industrial sandblast hose. They hid a sleeve inside to mask the true ID of the tube and did some creative tuning to overcome the shortcomings. Sonny was fast because he was a outstanding rider. So when the races start, they went to the line with the normal setup they had kept hidden. Mind games! *dunno* There is rules for being able to race with what you qualified with, But the game was simply, keep the other racers guessing.
Here is a Unit A65 Tracker that illustrates a extended intake .
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Eh, went on a roll there and forgot to address one issue.
This could be helpful as well See: https://jrcengineering.com/technical-support/jrc-pwk-carb-instructions/
Also: Additional information on your JRC carburetor.
Accessories and kits available;
1. Cable operated choke assembly for single , twin , and 3 cylinder applications
2. Fuel line and fuel fittings to make custom fuel lines
3. Air filters , custom and original type
4. Throttle cables for single , twin or 3 cylinder applications
5. Carburetor kits for Norton Commando single 30 or 32mm
6. Carburetor kit for TR6/7 to fit standard air filter box, 30mm
7. Carburetor kit for T140E 1979-82, replaces Mk2 Amal or Bing
8. Carburetor kit for new Royal Enfield 500, 30 or 32mm
9. Carburetor kit for Ural twins
10. Trident and Rocket 3 gantry conversions to keep stock air box and gantry
&
Check out our carb fitted to various applications. Click the links below:
Triumph Bonneville 650 – pair 30mm
Triumph TR6 – 30mm
Triumph TR7 – 30mm
Triumph Daytona 500cc – pair 26mm
Triumph Bobber 500cc – pair 26mm
Triumph Trophy 500cc – 26mm
Triumph and BSA 3 Cylinder Machines – three 26mm
Triumph and BSA Unit Singles 250-500cc – 26mm
BSA A7 500cc – 26mm or A10 30mm
BSA A50 -26mm BSA A65 -30mm
Norton Commando 750 and 850 – pair 30mm
Norton Commando 750 or 850 Single carb -32mm
Norton 500 Single – 26mm
Royal Enfield 350 Bullet – 26mm or 500 Bullet 30mm
Royal Enfield 500 Bullet – AVL motor – 32mm
Royal Enfield 750cc twin – pair 30mm
Ural Dneper 750 – pair 30mm
Douglas Dragonfly – pair 26mm
Moto Guzzi V50 500 V twin – pair 26mm
Ariel Square 4 1000cc – 30mm
Montgomery Wards Lawn Tractor -26mm
As to sizing of whats available, I Did talk to Bill and his guys at JRC about this. Its always a guess what to offer and what the marketplace will respond too, further, then it comes down to What can you source or what can you get manufactured? ** (See below for more fun with manuf)
So IIRC and I will resubmit this today for any update, But my understanding was to try and offer the basics for what most will order. Triples, singles and twins. While a 26mm-28mm-30mm &32mm all were fitted to BritIron at one time or another by Amal, They were limited on carb bodies sourceable. Originally Bill tried a lot of different companies to supply replacement carbs, And there is a lot of issues in investment, engineering and then having a marketable product, many of which the consumer never sees. So that is why what they have is whats on the market.
Keep in mind also, Different carbs respond in their own way. A round slide carb does not function the same as a flat slide design. A VM round slide style Mikuni does not function at all like a CV style Mikuni and the sizings are different for the same size motor. Secondly, RPM and usage, as well as temp and altitude impact as well. I built a 71 Bonnie for a customer and we fitted 28mm twin carbs as he rode it primarily in city traffic and urban areas, Rarely ever saw RPMs over 3500 and no freeway-interstate riding. With 30s or 32s, it was just a dog.
I serviced for many years a Triumph with a big bore kit (810cc) with dual 34mm carbs and it was a dog off the line but once you got it up to 5000+ RPM it just kept accelerating. Was not much fun to ride on the street except the odd track day when they allowed street bikes on.
In hot rodding days with cars, people chronically overcarbed. Common to see a SBC 350CI engine with Holley 750 and 850 double pumpers with a 600cfm with vac secondaries was faster, more power, more responsive and gas mileage was around 15-20 mpg vs the 850 double pumper which was a dog off the line and managed 8 mpg.
And heres a link to an interview with Sonny where he talks about psych tricks and racing..
See: https://www.soloshawn.com/sonny-burres.html
Heres some period race clips, Sonny winning Peoria TT in 1975, along with interviews of others.
See: https://www.superbikeplanet.com/1975-dirt-track-footage-sonny-burres-gary-scott/
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I was in a discussion about manufacturing, JRC is coming out with some very cool flat track racing and desert racing reproductions. Bates type seats, Belly pans, and air boxs. One discussion is the old flat blade type fenders many 50s and early 60s racers used. While its not complicated to make these, Many people want a ready to install kit along with fender stays.
Materials wise, here in the US, its a problem. My wife is logistics lead for a machine shop as well as Master scheduler. Getting tooling, materials and machine time is a complicated juggling act. While there is a lot of news medic covering trade issues, tariffs and import/export in global news, Here is the real problem.
Many large companies are now hedging their bets and stockpiling certain types of materials, which can complicate sourcing certain specs and dimensions. US made stainless, steel, aluminum, copper & Brass is a very volatile market. Imported materials rarely meet spec, and JRC told me that there is a worldwide shortage of Stainless steel fenders for certain British bikes because the Eastern Europe and Asian made stainless sheet has issues. When stamping in a die press the Stainless work hardens and cracks too easily.
Industry wide, there is a ongoing issue with this, I know personally I get about a email or phone call every week asking If I have any stainless fenders laying about. Even used ones.
My wife had ordered some specialized mill run copper tubing for a customer job and it was damaged in transit. Insurer and transport company suggested "Why not just bend it back???" *eek* *problem* *work*
So, its scrap. The mill said, it will be 6 months before they make any more. The customer is NOT happy.
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Sluggo
Thanks for the advice and information, sourced viton o ring for the flange and stainless steel braided fuel lines.
Just awaiting new inline fuel filter before its first run out.
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Billy, I am sure you will be pleased, please update with feedback, Any support needed, feel free to reach out either here or PM.
**NOTE** For some reason admin relocated this topic, looks like we are in Amal carb section now which kind of make sense...
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Hello Doug,
Thank you for the input regarding the JRC Superior carburetor. There are some folks out there who already have their minds made up. If we can educate a few of them we would be happy to do so. Our PWK carburetor has recently been updated to the Powerjet style. I have attached a recent new release we sent out be email. Available bore sizes and mounting styles are listed: https://mailchi.mp/9ab2c6a3be5a/jrc-superior-britflow-carburetor-updates?e=140ab0d3de
Those unfamiliar with carburetor tuning seem to be the ones with the most complaints. Followed closely by the purist who would never fit one just because it was not factory. When we know the application we pre-jet the product to avoid much of the bothersome tuning experience. The cheap products online are like you said of unknown quality. Many are fitted with odd size jets and jet carriers. This makes tuning almost impossible.
We will put out some articles soon on the subject.
Regards,
Nick Willcutt
Like us on Facebook to get the most current parts news:
https://www.facebook.com/JRC-Engineering-Inc-440670806095463/
JRC Engineering Inc
3110 Indian Ave Ste E
Perris, California 92571
USA
jrcengineering.com
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(Here is the text of the eBlast, Pix should be linkable, if not ask and Ill post them, as you can see these are a newer version and offer some great features)
The JRC Superior Britflow carburetor is intended to be a direct replacement for the factory supplied carburetor.
Why replace the stock carburetor with a JRC Superior?
Here are a few reasons:
Price - Our carburetor is an economical alternative to the OEM carburetor.
Performance - In dyno testing our carburetor was shown to increase horsepower and fuel economy. We have the data if you would like to see for yourself.
Safety - Our carburetor does not leak when "choked" for starting. So no fuel dribbling down the side of the carb. The flat slide design prevents throttle valve sticking. The bodies of our carb is not prone to warp if the flange bolts are over tightened.
Material - JRC Superior carbs are made of aluminium with a chrome plated brass slide. We do not employ pot metal in our carburetor. This makes the unit lighter and longer lasting.
JRC POWER JET - OUR LATEST VERSION OF THE SUPERIOR CARBURETOR
THE ADDITION OF THE POWER JET IMPROVES TOP END PERFORMANCE.
https://jrcengineering.com/product/jrc-power-jet/
OFFERED IN THE FOLLOWING BORES - 30mm, 28mm, 26mm, 24mm, 21mm
Also in 32 and 34mm
SEE OUR CARB MOUNTED TO VARIOUS APPLICATIONS AT THE END OF OUR TECH PAGE:
https://jrcengineering.com/technical-support/jrc-pwk-carb-instructions/
JRC-30PJ
30MM POWERJET - STANDARD 2 INCH MOUNTING FLANGE - FITS MOST BRITISH BIKES - TRIUMPH, BSA, NORTON, VELOCETTE, ETC
just a few application pictures:
TRIUMPH TR6 https://jrcengineering.com/wp-content/uploads/2017/09/tr6pwk.jpg
BSA A65 https://jrcengineering.com/wp-content/uploads/2018/04/A65.jpg
JRC-26PJ
26MM POWERJET - STANDARD 2 INCH MOUNTING FLANGE - FITS MOST BRITISH BIKES - TRIUMPH, BSA, NORTON, VELOCETTE, ETC
ALSO CAN SUPPLY IN 28, 24, 21MM BORES
JRC-30PJ/E
30MM POWERJET - 38MM SPIGOT - REPLACED AMAL MK2 - NEW URAL 750
JRC-30PJ/B
30MM POWERJET - 35MM SPIGOT
JRC-26PJ/E
26MM POWERJET - 38MM SPIGOT -
JRC-26PJ/B
26MM POWERJET - 35MM SPIGOT
ALSO CAN SUPPLY IN 28, 24, 21MM BORES WITH 2 INCH FLANGE
JRC-32PJ
32MM POWERJET - 38MM SPIGOT - NOT AVAILABLE IN 2 INCH FLANGED
JRC-34PJ
34MM POWERJET - 38MM SPIGOT - NOT AVAILABLE IN 2 INCH FLANGED
JRC-30PJ/A
30MM POWERJET - 58MM FLANGE - 2005-NEWER 500 ENFIELD BULLET
JRC-26PJ/A
26MM POWERJET - 58MM FLANGE - 2005-NEWER 350 ENFIELD
JRC-32PJ/A
32MM POWERJET - 58MM FLANGE - 2005-NEWER 500 ENFIELD AVL MOTOR
CUSTOM FITMENT REQUESTS ARE WELCOME.
THE FOLLOWING MOUNTING OPTIONS ARE AVAILABLE UPON REQUEST:
BORE SIZES JRC-30PJ, 28, 26, 24, 21mm:
(NO LETTER SUFFIX) STANDARD 2IN FLANGE
(B) 35mm spigot
(E) 38mm spigot - MK2 carb replacement/ New Ural 750
(A) 58mm horizontal flange - New Enfield
(C) 53mm vertical flange - Ural Dneper/ BMW
BORE SIZES: 32, 34mm
(NO LETTER SUFFIX) 38mm spigot - Norton 2-1 manifold kit
(A) 58mm horizontal flange - New Enfield AVL motor
CUSTOM FITMENT REQUESTS ARE WELCOME
THE FOLLOWING MOUNTING OPTIONS ARE AVAILABLE UPON REQUEST:
BORE SIZES JRC-30PJ, 28, 26, 24, 21mm:
(NO LETTER SUFFIX) STANDARD 2IN FLANGE
(B) 35mm spigot
(E) 38mm spigot - MK2 carb replacement/ New Ural 750
(A) 58mm horizontal flange - New Enfield
(C) 53mm vertical flange - Ural Dneper/ BMW
BORE SIZES: 32, 34mm
(NO LETTER SUFFIX) 38mm spigot - Norton 2-1 manifold kit
(A) 58mm horizontal flange - New Enfield AVL motor
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G'day Sluggo.
Thanks for posting that.
I'm a very happy customer.
Having two 30's on an A10 meant I had To "tune" them, and that took a bit of work, but great once sorted.
My only errr is the pilot screw on the right carb is hidden by the left carb. Not really a problem now their sorted.
Cheers
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First outing today with the SRM supplied PWK (JRC) 30mm carb, started first kick with use of the enricher, pulled well but popped on overrun, quick stop after 10 miles for adjustments to air screw and plug chop. Very pleased, liked the choice of idle adjustment screw position and no more tickling. Just need more practice of use of enricher.
Pilot jet 35
Main jet 134
Needle position middle
Air screw 1 1/2 turns
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A couple of pics of PWK carb on my Super Rocket
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Missed a pic
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I passed on your comments and a copy of your pix to the staff at JRC. Got this in return.
Hey Doug,
Tuning has been an issue when we introduce a carb to a new market. We always are seeking jetting data. That why the next customer in that region will benefit. Fuel formulations vary considerably since most vehicles are fuel injected these days. Any difference is compensated for by the computer. Not really to good for us. The addition of ethanol to fuel has also played a big part in tuning troubles.
We actually offer an extended pilot screw.
https://jrcengineering.com/product/p17a/
Regards,
Nick Willcutt
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G'day Sluggo.
I just downloaded their parts dogalog. Wow they have some stuff!
I looked at the link for the P17A and this is where the terminology of different countries become a problem. In the parts list it's called a idle screw, I know them as pilot screw (air in this case or fuel). What I call an idle screw they call throttle stop screw! So I took one out of a carb to compare to the pic on the web page. Yep their the tomartoes/tomaatoes.
Cheers
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Hi all, I have obtained a PWK carby from a friend that didn't use it, it was supposed to be jetted to suet the A7, it has main jet 115 idle jet 68 and JJH needle 26mm bore. Dose this sand right for the A7 iron head?
Any info would be appreciated.
Peter
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You may well have to try and see how she runs, saving grace the jets are plentiful and inexpensive, best of luck
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G'day Peter.
Idle jet way too big. Have a look here https://www.jrcengineering.com/technical-support/jrc-pwk-carb-instructions/
Cheers
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Thanks BB and Musky, Musky, I have had a look at that, but was hoping for some one that had fitted a PWK to come back with what jet size they ended up with for the 54 A7 iron head, could save a bit of work for me and others.
Peter
I E-Mailed JRC and got this reply, I might ad very promptly.
Hello Peter,
We have found the following specs work well for A7:
110 main jet, #35 slow jet. Is the richness you are encountering at idle or at a specific throttle position?
Regards,
Nick
JRC